Introduction

This document compares emission factors for Manchester and Melbourne. Manchester factors are from HBEFA; Melbourne factors are produced by COPERT Australia, and processed in emission factors.R.

COPERT Australia is an average speed model, unlike HBEFA which is a traffic situation model. The first (‘unspread’) set of comparisons in this document use Melbourne hot factors which (unlike the Manchester factors) do not include a ‘TrafficSit’ field with mutliple traffic situations. Instead, they have a ‘RoadCat’ field, with only 3 options: ‘Urban’, ‘Rural’ and ‘Highway’. Similarly, the ‘unbspread’ Melbourne cold start factors used in this document (unlike the Manchester factors) do not include an ‘AmbientCondPattern’ field. These factors are referred to as the ‘unspread’ factors.

A subsequent processing step in emission factors.R produces final Melbourne factors which do include ‘TrafficSit’ and ‘AmbientCondPattern’ fields. These are produced by shaping the unspread factors to match the spread of the Manchester factors across those fields.

manch_hot <- read_xlsx("./Manchester emission examples/EFA_HOT_Vehcat_healthModelMCR.XLSX")
manch_cold <- read_xlsx("./Manchester emission examples/EFA_ColdStart_Vehcat_healthModelMCR.XLSX")

melb_hot <- read.table("../data/processed/EFA_hot_melbourne_unspread.txt", header = TRUE, sep = ";")
melb_cold <- read.table("../data/processed/EFA_coldstart_melbourne_unspread.txt", header = TRUE, sep = ";")

melb_hot_final <- read.table("../data/processed/EFA_hot_melbourne.txt", header = TRUE, sep = ";")
melb_cold_final <- read.table("../data/processed/EFA_coldstart_melbourne.txt", header = TRUE, sep = ";")

Compare unspread hot emissions

The plots below compare Melbourne (Urban, Rural and Highway) values with the range of Manchester ‘TrafficSit’ values, for each pollutant (‘Component’) and vehicle category (‘VehCat’) combination. For each combination, there is a set of plots showing the different gradient values.

The Components covered are ‘NO2’, ‘PM2.5’ and ‘PM2.5 (non-exhaust)’. The VehCats covered are ‘pass. car’, ‘LCV’, ‘HGV’ and ‘urban bus’.

Because of the large number of Manchester ‘TrafficSit’ values, the y-axis of each plot is very crowded, so the plot sets in this document will only give an impressionistic view of how the Melbourne blue values compare against the overall set of Manchester grey values. A full set of individual plots is also saved to the EFA_plots directory, and can be viewed there to show more detail than is visible in the compressed plots in this document.

The table below shows the Melbourne hot values as a proportion of the mean Manchester values. For example, a value of ‘1’ would mean that the Melbourne value equals the Manchester value; ‘0.5’ would mean that the Melbourne value is half of the Manchester value.

For this purpose, only the Melbourne Urban and Rural values are used (not Highway). They are compared to the mean of the Manchester values with an ‘URB’ or ‘RUR’ TrafficSit respectively. Note that comparison to the mean gives only a rough-and-ready comparison; a more accurate comparison would require a weighted mean of the Manchester values, with weights determined by the distance travelled in each TrafficSit category.

The table highlights Melbourne values which are less than half or more than double the corresonding mean Manchester value.

Component RoadCat VehCat -6% -4% -2% 0% +2% +4% +6%
NO2 Urban pass. car 0.09 0.08 0.09 0.11 0.15 0.16 0.15
NO2 Urban LCV 0.2 0.16 0.29 0.34 0.22 0.27 0.31
NO2 Urban HGV 0.07 0.11 0.33 0.56 0.94 1.4 1.78
NO2 Urban urban bus 0.03 0.05 0.16 0.25 0.38 0.5 0.57
NO2 Rural pass. car 0.04 0.03 0.05 0.09 0.1 0.1 0.11
NO2 Rural LCV 0.09 0.07 0.2 0.23 0.24 0.37 0.4
NO2 Rural HGV 0.04 0.04 0.19 0.6 1.23 1.79 2.31
NO2 Rural urban bus 0.01 0.01 0.06 0.17 0.32 0.41 0.47
PM2.5 Urban pass. car 0.23 0.21 0.33 0.84 1.1 1.26 1.34
PM2.5 Urban LCV 0.39 0.35 0.93 1.9 2.42 2.74 3
PM2.5 Urban HGV 1.13 1.6 2.35 2.41 2.66 3.14 3.48
PM2.5 Urban urban bus 0.71 1.04 1.53 1.52 1.7 2.23 2.39
PM2.5 Rural pass. car 0.1 0.09 0.28 0.65 0.9 1.01 1.05
PM2.5 Rural LCV 0.12 0.1 0.75 1.27 1.6 1.77 1.91
PM2.5 Rural HGV 0.48 0.49 1 1.41 2.01 2.46 2.87
PM2.5 Rural urban bus 0.33 0.34 0.71 0.97 1.37 1.98 2.21
PM2.5 (non-exhaust) Urban pass. car 0.36 0.36 0.36 0.36 0.36 0.36 0.36
PM2.5 (non-exhaust) Urban LCV 0.96 0.96 0.96 0.96 0.96 0.96 0.96
PM2.5 (non-exhaust) Urban HGV 0.27 0.27 0.27 0.27 0.27 0.27 0.27
PM2.5 (non-exhaust) Urban urban bus 0.27 0.27 0.27 0.27 0.27 0.27 0.27
PM2.5 (non-exhaust) Rural pass. car 0.2 0.2 0.2 0.2 0.2 0.2 0.2
PM2.5 (non-exhaust) Rural LCV 0.23 0.23 0.23 0.23 0.23 0.23 0.23
PM2.5 (non-exhaust) Rural HGV 0.15 0.15 0.15 0.15 0.15 0.15 0.15
PM2.5 (non-exhaust) Rural urban bus 0.15 0.15 0.15 0.15 0.15 0.15 0.15

The next table shows a similar comparison, but also using the Melbourne Highway values. For this comparison, Manchester ‘Motorway-Nat.’ and ‘Semi-Motorway’ values (whether Urban or Rural) are compared to Melbourne Highway values. Other Manchester Urban and Rural values continue to be compared to Melbourne Urban and Rural values respectively.

That is, the green traffic situations in the diagram below are treated as ‘Highway’, while the others continue to be treated as ‘Urban’ or ‘Rural’.

Component RoadCat VehCat -6% -4% -2% 0% +2% +4% +6%
NO2 Urban pass. car 0.09 0.08 0.09 0.11 0.15 0.16 0.15
NO2 Urban LCV 0.2 0.16 0.29 0.35 0.23 0.28 0.32
NO2 Urban HGV 0.07 0.11 0.33 0.55 0.9 1.35 1.72
NO2 Urban urban bus 0.03 0.05 0.15 0.24 0.36 0.49 0.56
NO2 Rural pass. car 0.03 0.03 0.05 0.09 0.1 0.1 0.11
NO2 Rural LCV 0.09 0.07 0.21 0.24 0.25 0.39 0.42
NO2 Rural HGV 0.04 0.04 0.19 0.57 1.16 1.69 2.18
NO2 Rural urban bus 0.01 0.01 0.06 0.16 0.31 0.4 0.46
NO2 Highway pass. car 0.04 0.05 0.11 0.12 0.14 0.15 0.15
NO2 Highway LCV 0.06 0.12 0.21 0.31 0.34 0.36 0.37
NO2 Highway HGV 0.04 0.04 0.23 0.93 1.9 2.67 3.44
NO2 Highway urban bus 0.01 0.01 0.06 0.2 0.35 0.41 0.45
PM2.5 Urban pass. car 0.22 0.2 0.32 0.83 1.1 1.28 1.38
PM2.5 Urban LCV 0.38 0.34 0.92 1.88 2.4 2.75 3.02
PM2.5 Urban HGV 1.06 1.51 2.22 2.29 2.53 2.99 3.31
PM2.5 Urban urban bus 0.69 1.01 1.49 1.51 1.69 2.15 2.31
PM2.5 Rural pass. car 0.09 0.09 0.28 0.65 0.9 1.04 1.1
PM2.5 Rural LCV 0.11 0.1 0.74 1.26 1.58 1.78 1.91
PM2.5 Rural HGV 0.44 0.45 0.92 1.32 1.87 2.3 2.69
PM2.5 Rural urban bus 0.31 0.32 0.67 0.97 1.41 1.88 2.12
PM2.5 Highway pass. car 0.07 0.08 0.52 0.81 0.95 0.97 0.93
PM2.5 Highway LCV 0.09 0.48 1.02 1.44 1.66 1.65 1.73
PM2.5 Highway HGV 0.72 0.76 1.56 2.22 3.16 3.81 4.45
PM2.5 Highway urban bus 0.36 0.42 0.88 1.09 1.46 2.6 2.84
PM2.5 (non-exhaust) Urban pass. car 0.36 0.36 0.36 0.36 0.36 0.36 0.36
PM2.5 (non-exhaust) Urban LCV 0.94 0.94 0.94 0.94 0.94 0.94 0.94
PM2.5 (non-exhaust) Urban HGV 0.26 0.26 0.26 0.26 0.26 0.26 0.26
PM2.5 (non-exhaust) Urban urban bus 0.26 0.26 0.26 0.26 0.26 0.26 0.26
PM2.5 (non-exhaust) Rural pass. car 0.2 0.2 0.2 0.2 0.2 0.2 0.2
PM2.5 (non-exhaust) Rural LCV 0.22 0.22 0.22 0.22 0.22 0.22 0.22
PM2.5 (non-exhaust) Rural HGV 0.14 0.14 0.14 0.14 0.14 0.14 0.14
PM2.5 (non-exhaust) Rural urban bus 0.15 0.15 0.15 0.15 0.15 0.15 0.15
PM2.5 (non-exhaust) Highway pass. car 0.15 0.15 0.15 0.15 0.15 0.15 0.15
PM2.5 (non-exhaust) Highway LCV 0.18 0.18 0.18 0.18 0.18 0.18 0.18
PM2.5 (non-exhaust) Highway HGV 0.11 0.11 0.11 0.11 0.11 0.11 0.11
PM2.5 (non-exhaust) Highway urban bus 0.11 0.11 0.11 0.11 0.11 0.11 0.11

Comments on hot emissions

  • There is little difference between the results in the two tables. The comments below use figures from the second table (Urban/Rural/Highway), but similar comments apply to the figures from the first table (Urban/Rural).

  • For NO2 emissions, the Melbourne values are much lower than the Manchester values, for all categories except HGV. For example, considering the table comparing Melbourne values with mean Manchester values, for Urban passenger cars, the Melbourne values are around 10% of the Manchester values. For Urban HGV, the difference is smaller, though at 0% gradient the Melbourne values are still only around 50% the mean Manchester values. And for HGV, the spread between values for negative and positive gradients is greater for Melbourne than for Manchester, with the Melbourne negative gradient values being much lower than the Manchester values, and the Melbourne positive gradient values being much higher. For example, for Urban HGV, at 0% the Melbourne values are 0.55 times the Manchester values; at -6% the Melbourne values are 0.04 times the Manchester Values; and at +6% the Melbourne values are 1.72 times the Manchester values.

  • The PM2.5 Melbourne values are generally closer to the Manchester values, especially at 0% gradient. For example, for Urban passenger cars, the Melbourne values are 0.83 times the Manchester values. However, as with NO2 values, the spread between values for negative and positive gradients is greater for Melbourne than for Manchester. For example, for Urban passenger cars, the Melbourne values are 0.22 and 1.38 times the Manchester values for -6% and +6% respectively.

  • For PM2.5 (non-exhaust), note that there is no variation by gradient. For Urban LCV, the Melbourne values are very close to the Manchester values (0.94). However, for other categories the Melbourne values are much lower, ranging from 0.11 to 0.34 times the Manchester values.

Compare unspread cold start emissions

The plots below compare the Melbourne values (which are all Urban) with the range of Manchester ‘AmbientCondPattern’ values (which, again, are all for Urban roads), for each pollutant (‘Component’) and vehicle category (‘VehCat’) combination.

The Components covered are ‘NO2’ and ‘PM2.5’. ‘PM2.5 (non-exhaust)’ is not relevant (and not provided for either city) as it relates to tyre, brake and road abrasion emissions which do not occur merely as a result of starting the vehicle . While the VehCats covered in the Melbourne cold start data are ‘pass. car’, ‘LCV’, ‘HGV’ and ‘urban bus’, the Manchester cold start data only includes ‘pass. car’ and ‘LCV’. Accordingly, plots are only produced for these VehCats.

A full set of plots is also saved to the EFA_plots directory, and can be viewed there.

The table below shows the Melbourne cold start values as a proportion of the mean Manchester values. For example, a value of ‘1’ would mean that the Melbourne value equals the Manchester value; ‘0.5’ would mean that the Melbourne value is half of the Manchester value.

Only Urban values are shown (because both Melbourne and Manchester only have values for Urban roads). And only ‘pass. car’ and ‘LCV’ values are shown, because Manchester does not have values for ‘HCV’ or ‘urban bus’ (though Melboune does).

The Melbourne Urban values are compared to the mean of the values for all Manchester AmbientCondPattern categories. Note that comparison to the mean gives only a rough-and-ready comparison; a more accurate comparison would require a weighted mean of the Manchester values, with weights determined by the distance travelled in each AmbientCondPattern category.

The table highlights Melbourne values which are less than half or more than double the corresonding mean Manchester value.

Component RoadCat VehCat proportion
NO2 Urban pass. car 1.87
NO2 Urban LCV -0.76
PM2.5 Urban pass. car 1.87
PM2.5 Urban LCV 7.32

Comments on cold start emissions

Looking at the table comparing Melbourne values with mean Manchester values, for passenger cars, the Melbourne values are almost double the Manchester values for both NO2 and PM2.5.

For LCV, the Melbourne PM2.5 values are over 7 times the Manchester values. For LCVs, the Manchester NO2 values are negative figures. It is understood that this is intended, with the total emissions being a combination of the hot and cold start values.

Compare spread hot emissions

This part of the document re-runs the hot emission plots above using the ‘spread’ emissions, where the Melbourne Urban, Rural and Highway emissions have been spread into multiple ‘TrafficSit’ categories, to match the shape of the spread of equivalent Manchester emissions. For this purpose, for each combination of vehicle, road category and pollutant, a reference Manchester traffic situation is selected, being the traffic situation with the closest speed (V_weighted) to the average speed used by COPERT Australia. Factors for the Manchester traffic situations are calculated as the emission for the traffic situation divided by the emission for the reference situation. Each of the Melbourne Urban, Rural and Highway emission values is then spread into multiple traffic situations, by multiplying the value by the Manchester factor for that traffic situation.

Compare spread cold emissions

This part of the document re-runs the cold start emission plots above using the ‘spread’ emissions, where the emissions have been spread into multiple ‘AmbientCondPattern’ categories, to match the shape of the spread of equivalent Manchester emissions. For this purpose, for each combination of vehicle and pollutant, the average of the Manchester values for that combination is selected as a reference value. Factors for the Manchester ‘AmbientCondPattern’ categories are calculated as the emission for the pattern divided by the reference value. Each of the Melbourne emission values is then spread into multiple ‘AmbientCondPattern’ categories, by multiplying the value by the Manchester factor for that category.